Format tunnel IDs consistently.

Format tunnel IDs consistently.

Some code failed to convert tunnel IDs to host byte order for printing,
so this fixes that.  Some code printed tunnel IDs with a 0x prefix and
other code didn't, so this code uses the '#' flag consistently (which
prints 0x for nonzero values and omits it for zero).

This commit also stops always printing all 8 digits.  When tunnel IDs
are expanded to 64 bits, as they will be soon, printing 16 digits all the
time wastes too much space.

Acked-by: Jesse Gross <jesse@nicira.com>